Air compressors for commercial vehicles as a rule convert a rotational movement of at least one piston, which rotational movement is provided by the drive source (engine), which piston moves up and down in a cylinder and compresses the air during said movement. Said conversion takes place by way of a connecting rod which is mounted rotatably on the piston by way of a connecting rod eye and which is mounted on a crankshaft such that it can be rotated eccentrically by way of another connecting rod eye. The crankshaft is set in rotation by the drive source by way of a transmission ratio. The transmission ratio is constant, with the result that the operating speed of the compressor changes with the engine rotational speed.
The compressor is generally designed in such a way that it can still deliver the required compressed air requirement of the vehicle at its system pressure, even during idling of the vehicle engine. Here, the compressor has to fit into an installation volume which is predefined by the vehicle design, and the crankshaft has to have a gearwheel for the transmission of power, which gearwheel fits into a gearwheel which is present on the drive source. The operating parameters of the compressor are therefore specified to a more or less fixed extent and have to be accepted by the user, even if they should not be optimum with regard to noise or energy consumption.